B-58 Primary Construction
In September final evaluation of the competing designs by the Wright Air Development Center left little doubt about the forthcoming decision. The center thought that the Boeing MX-1965 design would produce either an aircraft of small size with mediocre supersonic speeds or one so large as to almost preclude any supersonic capability. The Boeing supersonic bomber design was conventional. It featured wings swept at 35 degrees, an internal bomb bay, a fore and aft bicycle landing gear which, like that of the B-52, retracted into the fuselage. It called for 4 engines, similar to those proposed for the Convair bomber, but integral with the wing, 2 on each side, tucked inboard against the fuselage. It projected a supersonic speed of Mach 1.8 at 55,000, but promised plenty of room for its 3-man crew. Maximum take-off weight was about 156,000 pounds.
On the other hand, the MX-1964 design, already nicknamed the "Hustler" by Convair, provided the more promising means of achieving supersonic speeds with a weapon system of minimum size. In addition, the center felt that the Convair approach best satisfied the "spirit" of the Development Planning Objective for Strategic Air Operations during the period 1956-1960. This objective, issues by the Air Force on 29 May 1952, favored a small bomber and underlined that future strategic aerial warfare could be most economically and effectively accomplished by a "combination system that incorporates a tanker cargo airplane for refueling in flight the combat zone airplane."
The small bomber concept, embodied by the Development Planning Objective of May 1952, reflected the opinion of Col. Bernard A. Schriever, the USAF Assistant for Development Planning in the Office of the Deputy Chief of Staff for Development, and had been endorsed by the Air Force Council and Gen. Hoyt S. Vandenberg, Chief of Staff of the Air Force. But this Development Planning Objective of May 1952 also ran counter to many established principles. SAC officials and particularly General LeMay, who by 1952 had been heading the command for several years, generally favored large bombers, capable of greater ranges. "Even though the best intercontinental bomber available requires some refueling;" SAC insisted, "it does not follow necessarily that the optimum system requires a bomber which has no intercontinental capability without refueling." The command argued that "high performance alone" could "never insure mission success" against targets defended by modern interceptors and surface-to-air missiles, and pointed out that the small supersonic bomber's lack of range would prevent it from operating without refueling from most forward operating bases. Also, crew members would be very confined in such a small bomber.
Finally, instead of fostering economy and reliability, combining unconventional design and operational techniques made "it entirely possible that the system might prove operationally unsuitable." SAC's arguments notwithstanding, a decision was near. In an unusual step, the decision makers would totally disregard SAC's concern. In late October, following ARDC's thorough review of the Wright Air Development Center's conclusions, Lt. Gen. Earle E. Partridge, the ARDC Commander, recommended to Headquarters USAF that the competition between Boeing and Convair be stopped immediately. General Partridge noted that the MX-1964 supersonic drag and gross weight figures appeared optimistic, and if true, this would further limit the aircraft's range. Also, costs had not been considered properly, and the forecast operational date would inevitably slip, perhaps to 1959. Nevertheless, the ARDC Commander endorsed prompt selection of the Convair project and asked that accelerated development of General Electric's J53 engine (from which the J79 derived) be authorized without delay. This was approved by the Weapons Board, the Air Force Council, and by General Vandenberg on 18 November 1952. Soon informed that the design competition was ended, Boeing reportedly took the bad news well.
The Air Force selection of Convair over Boeing was not a blanket endorsement of the MX-1964 design. It took several months and many consultations between Convair, National Advisory Committee on Aeronautics, AMC, ARDC, and Wright Air Development Center personnel to settle on a definite configuration which, as it turned out, was subjected to many later revisions. These initial delays were not unfounded. Development problems with the Convair F-102 interceptor were confirming the Air Force's suspicion that the contractor had failed to make proper allowance for the aerodynamic drag of a delta-wing aircraft, be it a fighter or a bomber. Moreover, the area-rule concept of aircraft design," discovered by National Advisory Committee on Aeronautics researcher Richard T. Whitcomb, had been verified during December 1952 in the agency's new transonic wind tunnels. This concept held that interference drag at transonic speed depended almost entirely on the distribution of the aircraft's total cross sectional area along the direction of flight. The solution was to indent the fuselage over the wing to equalize the cross section areas (and thus the volume) at all stations, thereby producing the so-called "coke bottle" or "wasp waist" configuration. Yet, as in the F-102's case, Convair did not accept the Whitcomb findings until its own engineers had confirmed their validity. Another delaying factor was the absence of military characteristics, which were deferred until the fall of 1953.
Although the MX-1964 design was yet to be finalized, the Air Force proceeded with specific plans. In December 1952, the Deputy Chief of Staff for Development endorsed a production schedule developed by the Wright Center. This schedule was based on the 4-year procurement of 244 B/RB-58s (more than twice the final total). Thirty of these aircraft, with the first one due for delivery in January 1956, would be used for testing, while preparations would be made for full scale production of a version incorporating all test-dictated changes. The 30 initial planes would then be reworked on the production line into the approved configuration. This plan, drawn from the "Cook-Craigie production policy;" was expected to eliminate the faults in a basic design before many aircraft had been built and to speed the acquisition of operationally effective weapon systems (The Cook-Craigie production plan was actually a mere concept, developed in the late forties by USAF Major Generals Laurence C. Ctaigie, Deputy Chief of Staff for Development, and Orval R. Cook, Deputy Chief of Staff for Materiel. They both knew this concept could be expensive and thought "it was only applicable where you had a high degree of confidence that you were going to go into production."
The F-102, a by-product of the "1954 Interceptor;' bared some of the pitfalls of the Cook-Craigie plan for early tooling. In October 1953, when testing established unequivocally that important changes had to be made to the F-102's design, 20,000 of the 30,000 tools already purchased by Convair had to be discarded.). Recent experiences seemed to justify such an approach. Building aircraft prototypes before selecting one of them, as occasionally done, had proved costly and time consuming. Moreover, the selected prototype, once produced, has often still been found to have design flaws that needed correction. In any case, the Cook-Craigie philosophy, if not an integral part of the weapon system concept, fitted it perfectly. The weapon system concept itself promoted significant changes and therefore more planning.
In early 1953, General Putt, ARDC's new Vice. Commander, announced the Air Force's revised management tasks. The B-58 weapon system would require a minimum of government-furnished equipment since the prime contractor would be responsible for system design and engineering and would deal directly with subcontractors to acquire major components. The Wright Air Development Center, now headed by Maj. Gen. Albert Boyd, would contract for major components "only when limitations of industry, operations, or logistic considerations force the USAF to control source and/or methodology." Even then, such components would have to be designed, built, and tested to Convair's specifications. In short, the Air Force's role was to monitor the prime contractor's plans and progress; to approve specifications as well as subcontractors, and to supply the money. It also retained the right to veto any developments that could cause operational or logistical problems. The Air Force management of the B-58 weapon system would be exercised at the Wright Air Development Center by a 20-man joint project office, made up of ARDC and AMC representatives.
Contracting proved to be a difficult endeavor, far more complex than usual. Limited experience with the weapon system concept prolonged negotiations, as the Air Force and Convair worked out specific provisions to define each party's prerogatives and responsibilities. These clauses became part of Convair's letter contract on 12 February 1953, when a supplemental agreement was signed. This was the fifth and so far most significant amendment to Letter Contract AF33(038)-21250. The contract itself was not finalized until the end of 1955, even though the letter contract dated back to February 1951. This was an important turning point, indicating the B/RB-58 program was getting under way, with the B-58 mockup scheduled for the end of the summer, while that of the reconnaissance version would follow in the fall of 1953. The amendment also gave Convair $22 million to cover pre-production planning costs and the acquisition of long-lead time tools and equipment. Yet, it failed to resolve immediately a few basic problems. As single manager, Convair believed that compensation for its additional managerial efforts should be incorporated in the program's direct cost.
The Air Materiel Command disagreed, contending that such payments should be added to the overhead administrative costs of present and future contracts, on a yearly pro-rated basis. AMC also postponed total approval of the funds requested by Convair to expand its Fort Worth facilities, causing the contractor to spend $500,000 of its own to secure extra office space.
The Air Force selected a firm configuration for the B/RB-58 and authorized Convair to begin work on each full-scale mockup version. The approved design incorporated the changes dictated by the National Advisory Committee for Aeronautics's transonic area rule. Specifically,; the airplane cross-sectional area was redistributed longitudinally to minimize the compressibility drag rise encountered at transonic speeds. This had been accomplished by fuselage redesign, housing the engines in 4 staggered nacelles, and adding a 10-degree trailing edge angle to the wing, which also increased the wing area to 1,542 square feet. In addition, the wing's leading edge had been cambered and twisted to reduce drag at lift.
|Join the GlobalSecurity.org mailing list|